System is freezing after 8 to 10 hours of running

Followed by this link (http://www.tomshardware.com/forum/forum2.php?config=tomshardwareus.inc&cat=33&post=267468&page=1&p=1&sondage=0&owntopic=1&trash=0&trash_post=0&print=0&numreponse=0&quote_only=0&new=0&nojs=0) I thought everything was fine. But soon after that a new problem raised. If I run system for 8 to 10 hours or 5 hours it gets frozen state again. It mostly happen when I browse the net. I tested all latest browser and got the same result. If I play any music in background when I am on browsing sound gets crashed and screams like carrrrrr. The problem persist even after closing the browser. First, mouse pointer stops for a while then I can move it and again it stops. Keyboard also behave in same manner. When I tries to shut down my pc the system gets frozen when "Windows is shutting down" message appeared. My GPU core temperature is 61* C to 63* C (I have used HWMonitor). I have checked the BIOS. It shows CPU temperature is 30 to 31* C and System Temperature is 40 to 41* C.

I use wireless USB Modem. My OS XP service pack 2. Any suggestions?